Starting with nothing:
If you have no audio equipment in your vehicle, you'll need (at least) a head unit and a pair of speakers. Virtually all aftermarket head units have internal amplifiers. The exceptions are generally the top_of_the_line models. If you plan on upgrading to a system in the future, you'll want a head unit with at least one pair of preamp level (RCA) outputs.
Things You'll Need for a Basic Installation:
Strippers/Crimpers
Butt Connectors (red are most commonly needed for OEM wiring)
Speaker Wire (16g parallel zip cord is fine)
Tools to Remove the Head Unit (#2 Phillips screwdriver, 7mm nutdriver, a Torx T15 driver and a broad tipped regular screwdriver will get you a long way)
DIN Radio Removal Tool* ('U' shaped tool required to remove many of the newer car stereos - particularly Ford and Mazda)
*These tools are inserted into the 4 holes on your head unit (2 on each side). After inserting them, you pull them apart (away from the center of the head unit) and out toward you. Make absolutely sure that you've NOT inserted the tool on the radio side of latches. They MUST go to the outside of the spring latches. If they go to the between the radio and the spring latch and you bend the latches too far out, you may have to tear the dash apart to get the head unit out.
Basic Stereo Unit and 2 Speaker Installation:
We are mainly dealing with the electrical aspects of an installation here. Physical aspects like mounting and bracing won't be covered in any detail yet.
OK, these are the electrical connections that will have to be made. This assumes that there was an OEM stereo in the vehicle and it did NOT have external amplifiers.
Memory (12 volt constant source)
Ignition (switched 12 volt source - goes on and off with the key)
Ground
Left Speaker +
Left Speaker -
Right Speaker +
Right Speaker -
Power Antenna Remote (if the vehicle has a power antenna)
Antenna (arial)
All of these connections should be made using butt connectors and an aftermarket wiring harness adapter. You'll connect the new head unit's wires to the adapter harness. This will allow you to make all connection while leaving the stock harness intact. Some vehicles require antenna adapters. Check with your car audio dealer to see if you need one. If you have an older vehicle, it may have common grounded speakers. If this is the case, you will need to run new wires to the speakers. If in doubt, run new speaker wires. If you run new speaker wires, you'd connect the speaker output wires from the head unit directly to the new speaker wires.
Types of Connectors and Connections
Butt Splice Connectors:
The most common connector is the butt splice connector. It is generally a copper tube covered with a PVC insulator. Red connectors are designed to accept wires between 22g and 18g. Blue connectors are for wire sizes 14g to 16g. Yellow connectors are for 12g to 10g. For larger wire sizes, the colors start over again but the difference in size is so significant that you'll never be confused on which wire a given color connector is to be used.
Closed End Crimp Caps:
Many installers use closed end connectors with good results. For this type of connector, you strip the wires, twist them together, place the cap over the twisted wire and crimp it. They're especially good when you need to connect more than 2 wires.
Spade and Ring Terminals:
A red ring terminal is used for 6g wire. Blue terminals are designed for 14-16g wires. The yellow terminal is a standard spade terminal that's designed to work with 12-10g wires.
Push-on Terminals:
This type of terminal is used on most speakers.
Wire Nuts:
Many people use wire nuts when installing their stereos simply because they're available. For most all situations, wire nuts are not a good idea for car audio. When used for household wiring, they're used to connect 2 or 3 single stranded wires in a vibration free environment. If you were going to wire your house, this would be a good choice. For a car, it's a bad choice.
Scotch-Loks and T-taps:
Scotch Loks are used where you need to tap into a wire but don't want to have to cut it. They are most commonly used in situations like splicing in a boat trailer connector. You can tap into the brake and running lights without having to cut the wires.
Soldering:
Soldering is probably the most secure way of connecting 2 wires (if it's done properly). Solder has a fairly high resistance compared to copper. This means that you shouldn't rely on solder alone for a good connection. It has to be crimped also. A propane torch won't work well because it causes oxidation and will not allow the solder to 'stick'. The solder will just roll off of the oxidized copper. If you have to use a propane torch, heating the terminal from the back side (opposite the wire) will reduce the oxidation of the copper.
Connector Quality:
There are many low quality connectors on the market. Many of the types you get in cheap connector sets (with cheap crimping pliers) are made so cheaply with so little metal that they can NEVER make a good crimp. These are some other things that make good quality connectors. The best connectors have all of these features.
Funnel Entry Insulators:
Funnel entry is simply where the insulator forms a funnel inside of the insulator so that the wire doesn't catch on the edge of the copper connector as you insert the wire. If you are going to make a lot of connection, this is absolutely necessary.
Brazed Seams:
When most connectors are made, they are stamped from a flat sheet then formed to make a round connector. When this is done, the part where the 2 pieces meet can be left as_is or they can be brazed or soldered together. When this is done, it provides for a much more secure crimp (because the seam can't pull apart - which would relieve pressure on the crimp/wire).
Nylon Insulators:
Nylon insulators are somewhat tougher than PVC insulators. When crimped too hard, PVC often splits or breaks up. Nylon is much less likely to split or break apart.
Adding an Amplifier:
If your stereo unit has RCA/preamp outputs, adding an amp will be fairly easy. A little effort but nothing too difficult if you take your time and plan your installation. The hardest part is running the new power wire from the battery to the trunk (boot) of the vehicle. And no, you can't connect the amplifier's main power wire to the vehicle's fuse box.
These are the additional connections that you'll have to make:
Main Power Wire:
The main power wire must be connected to the battery. It must have an appropriately rated fuse in line (near the battery). The wire will have to pass through a grommet in the firewall, under the carpet and (generally) into the trunk. To get the wire into the trunk, you may need to remove the back seat. When you run it into the trunk, it generally has to pass over some sharp sheetmetal. If this is the case, take a piece of rubber heater hose and split it open. Open the hose and place it over the sharp sheetmetal. This will prevent it from cutting the wire. When making the connection to the battery, you'll usually use a large ring terminal. From the ring terminal you'll use a short length of wire to connect to the fuse holder. From the fuse holder, you'll run the power wire to the rear of the vehicle. In the rear of the vehicle, the power wire can be run either directly to the amplifier's positive terminal (if you have only one amplifier) or to a distribution block (if you have multiple amplifiers).
Signal Wire:
The amplifier needs some sort of signal to amplify. The best way to send it a signal is through the RCA cables. If your stereo unit does not have preamp outputs, using a Line Output Converter (LOC) is probably your best bet. Since you may not have any troubleshooting skills, the LOC is probably the best way to avoid trouble. Many times, the speaker level input of an amplifier will be poorly designed and will cause noise problems. There have even been a few speaker level inputs on amplifiers with a common ground input (very bad). Using the LOC avoids these problems.
Remote Power Wire:
The remote wire from the head unit tells the amp when to turn on and off. It is a low current control signal that runs from your head unit to the amplifier. It must be fused behind the stereo unit with a 0.5 amp fuse (1/2 amp).
Ground Wire:
The ground from the amplifier should be a short run of cable approximately the size of the amplifier's incoming power wire. It should be grounded to the floor pan of the vehicle. Don't skimp here, make sure you use an adequate size grounding wire and be even more sure of bolting it to a good ground and NOT your battery ground.
Speaker Wires:
The speaker wires will run from the amplifier outputs to the speakers. For connecting the amplifier to woofers in the trunk, a short run of 16g speaker wire will be fine. If you're connecting the amplifier to interior speakers (doors, dash, back deck), you must make sure that there are no inline OEM amplifiers. If there's any doubt, run new wires.
Read This - Caution - Read This
Any speakers that will be connected to the amp MUST be disconnected from the stereo unit. Sending the amplifier's output signal back into the speaker outputs of the stereo unit will frag the stereo unit.
Multiple Amplifiers:
When using multiple amplifiers, you'll have to do as above but a few more things come into play.
Power Wire:
The power wire will probably have to be larger. That's why it's good to look forward to what you want for your system. If you run a wire that's barely large enough for one amplifier, adding a second amp will require running a second wire (with its own fuse holder) or will require that you replace your existing wire. To split the power source to each amplifier, you'll need to use a distribution block. Use fused blocks for splitting the 12 volt line and only UNfused blocks for ground.
Electronic Crossovers:
When using multiple amplifiers, you generally split up the audio spectrum. This allows you to send the bass to larger speakers and the rest of the audio spectrum to interior speakers. Many amplifiers have built in crossovers and many of them are quite good but some are VERY poor. The poor ones generally have poor rolloff characteristics. Using a good quality external crossover solves this problem, It also puts all of the controls (level, crossover frequency, phase...) in one place. An external crossover also generally has more features than the crossovers built into the amplifiers. This can make it much easier to adjust the system.z
Signal:
When sending the signal to a single amplifier, you simply plug them directly into the amplifier. When you have multiple amplifiers, you have to get the signal to all of them. If you have only one pair of RCA cables, you can use y-cables. If you're using an external crossover, you can plug the RCAs into the input of the crossover. The crossover will then have multiple outputs. The low pass output will go to the bass amp. The high pass output will go to the highs amp. No y-cable will be needed unless you have multiple bass amps or multiple highs amps. Some amplifiers provide a pass-through or crossed over preamp output to go to another amp. This will also avoid the need to use y-cables.
Remote:
Since the remote signal is such a low current signal, it's ok to jump from amplifier to another with a relatively small wire (DO NOT SKIMP on power and ground wires though). Use nothing smaller than 16g because it's easier to get good connections with it than it is with very small wire. You 'could' use 22g but it's more likely to break and may not be held firmly by the clamps in the terminal block. This is especially important when the amplifier has tubular connectors with set screws.
Stereo Unit Power Output:
Many manufacturers inflate/exaggerate their specs/ratings. This is especially true for power amplifiers. Many head units claim that they can produce 40+ watts/channel. In fact, the true usable power is generally no more than 20 watts RMS per channel into a 4 ohm load.
2 Volt vs 4 Volt Preamp Outputs:
You don't need to have 4 volt preamp outputs to have a good sounding system. The quality of the stereo unit is much more important.
Distortion in Stereo Unit Amplifiers:
Many people claim that the stereo unit's internal amplifier is 'dirty'. This just isn't true. For the most part, the distortion levels are inaudible at any point up to the point of clipping. The reason that they believe that the internal amplifiers are distorted is because they need more than 20 watts per channel and they are driving the internal amplifiers into clipping. When they add an external amplifier, the external amplifier can produce more power before clipping than the internal amplifier could produce before clipping. This means that the external amp can play at the desired level without audible distortion. If both the internal and external amplifiers were played at the same level (neither clipping), the internal and external amplifiers would sound precisely the same (disregarding any equalization or filters that may be available on the external amplifier).
Speaker Wire Size:
You don't need to run large gauge speaker wire to have good quality sound. 16g lamp cord is perfectly fine in almost every situation. Even the stock wiring in the car is usually perfectly fine (the exception may be only when there are OEM amplifiers in line with the speakers). If someone tells you that you have to replace the stock speaker wires with large gauge wire to have good sound quality, they probably don't know what they're talking about.
Dual Voice Coil Woofers:
Dual Voice Coil (DVC) woofers are simply speakers with two voice coils wrapped around the same voice coil former. This allows the speaker to be connected in 2 different ways. With the individual coils wired in series, the resulting impedance will be 2 times the impedance of each individual coil. Wiring the coils in parallel will make the impedance 1/2 the impedance of each individual coil. This means that a speaker with dual 4 ohm coils can be wired to 2 ohms or 8 ohms.
Expensive Patch Cables:
You don't need to have $20/foot interconnects in your vehicle to have good sound quality. It's not even necessary to have shielded cable in all situations. Many people make their own preamp cables out of 20g or 18g primary wire. They take 2 single conductor stranded wires and twist them together with a cordless drill until they have 1-2 twists per inch. Then they simply solder the RCA connectors on the ends of the cable. Even cheap, thin RCA cables will work perfectly fine most of the time. If the audio equipment that you have has well designed input circuits, expensive cables are simply not needed.
Speaker Magnet Size:
Just because a speaker has a very large magnet, that does NOT mean that it's a great speaker. Many times, having a very large magnet just means that the speaker will be harder to drive. Many speakers use huge magnets to get you to buy them but the design is inferior to many of the truly great speakers like JL. There are many variables that determine speaker performance. Magnet size is just one variable.
Speaker Power Ratings:
Having a speaker with very high power ratings (even if the power ratings are legitimate) doesn't necessarily make it a good speaker for every application. Competition speakers that have huge magnets and can truly handle thousands of watts of power may not be the best choice for a moderately powered system. Speakers that are designed to handle 1000 watts of power probably will not be a good choice for those with only 200 watts of amplifier power. In many instances, having speakers that are honestly rated to handle about the same power as your amplifier's rated power output will perform best.
Stereo vs Mono:
Some people believe that a system can't be 'mono' unless the speaker (or speakers) is bridged onto the amplifier. If you have a 2 channel stereo amplifier and the same signal is driven into each channel, the output is mono (regardless of the number of channels or the number of speakers). To be true 'stereo', the signals driven into the left and right channels have to be different from one another.
Amplifier Bridging:
You don't have to bridge an amplifier to get full power from it. Running an amplifier at 2 ohms stereo will produce the same power as running it at 4 ohms mono. Running an amplifier at '2 ohms mono' will generally mean the end to it (exceptions - class D and high current class A/B amplifiers).
2 Ohm Stable:
When a multi-channel amplifier (2 or more channels) says it's two ohm stable, this generally means that it can drive a two ohm load with each channel. This doesn't mean it can drive a two ohm load when the amplifier is bridged. If it is two ohm stereo stable it is generally going to be able to drive only a 4 ohm (or higher) load when bridged
Disconnecting the Battery:
When installing a new system in your vehicle, you should remove the GROUND wire from the battery. It will prevent you from doing any damage to the vehicle's electrical system. It will also prevent your battery from being drained by the dome/hood/door lights. I know you want to listen to the radio while running all of the new wires and such. Do yourself a favor and GO FIND ANOTHER RADIO.
Routing Wires from the Stereo Unit:
To prevent radiated electrical noise from entering your system's signal line, you should avoid running the RCA patch cords along the the main power wire. It is OK for the power wire and the RCA cables to cross each other or even run together for a very short distance but you shouldn't run them together for any significant distance. One common solution is to run the RCA cables down the opposite side of the vehicle. The remote output lead from the stereo unit may be run down the same side as the main power wire (away from the RCA cables). Any speaker wires that run from front to back can be run down either side. Some people go the extra step and run speaker wires down the center of the vehicle but it's not necessary. They won't pick up any noise from the power wire and won't induce noise into the RCA signal lines. Again... Make sure that none of the wires will be damaged when the vehicle is reassembled.
Making the Connections to the Power Source:
Most amplifiers draw significant amounts of current (too much current to be drawn from the vehicle's fuse box). This means that you will have to make a connection to a more suitable point. Most of the time, the main power wire is connected to the battery's positive terminal. Since the battery is capable of supplying more than 1000 amps of current and your power wire can't likely safely carry that much current, you MUST have an inline fuse (this can not be stressed enough). The fuse must be rated to protect the power wire being used. If the power wire was unfused and accidentally shorted to ground, the wire and the vehicle would soon be fully engulfed in flames. The fuse holder should be between 6 and 18 inches from the battery. If it's too close to a standard lead acid battery, the fuse and holder may corrode like the positive battery terminal does. If it's too far away, it will not provide the required protection because there is too much unprotected wire (between the battery and the fuse).
Routing the Power Wire to the Rear of the Vehicle:
In many vehicles, there are unused rubber or plastic plugs in the firewall. These plugs can be removed and a small hole (size determined by the outside diameter of the wire) can be cut or drilled in it. The plug can then be replaced and the wire can be passed through the plug. If the angle of the plug will allow water to run around the wire and into the vehicle, use some silicone sealant to seal around the wire. Sometimes, there are extra 'nipples' on rubber plugs where the speedometer or other cables pass through the firewall. The tips can be cut off of the nipples and the wire can be passed through the firewall.
Drilling!:
If there is no place to run the wire (not likely), you will have to drill a hole. If you can not CLEARLY see both sides of the firewall where you want to drill the hole, DO NOT drill. There are many hazards to drilling through the firewall. You could puncture fuel lines, brake lines and wires. If you 'think' you know where the drill will pass through the firewall, you can use a center punch and make a small dent on one side then go around to the other side to see if you were right about the location. Many vehicles have 2 layers of sheet metal in the firewall area so this technique won't always work. After you drill the hole, make sure to use the appropriate grommet in the hole to prevent the wire from being cut on the sharp metal. If you don't have a grommet, you could possibly use a piece of heater hose or similar material (siliconed into place to prevent it from falling out of the hole). I know that some people will say that you should just get a grommet, but knowing human nature, I know that some people will try to run it through the FW without a grommet (or any protection) if they don't have one handy. The piece of rubber hose isn't a perfect solution but it may help protect the power wire for those too lazy to do it right.
Equalizers:
The first thing that you should know is that an equalizer is not designed to make a system louder. An equalizer will not make an amplifier put out any more power than without it if your stereo unit has a sufficient drive signal. An EQ is designed to smooth out the frequency response of your system. The most popular EQ is the preamp level graphic equalizer. It takes the signal from the RCA jacks on your head unit. This type of EQ is sometimes called a passive equalizer but this is not accurate. A preamp EQ is full of active filter circuits. All of the equalization is done by those active filters. There are different types of preamp EQs.
Graphic Equalizers
The graphic equalizer gets its name because its sliders will form a graphic representation of the boost or cut in the audio output. Each of the sliders boost or cut a small section of the audio spectrum at a predetermined frequency. Usually the lower frequency (bass) sliders will be on the left. The high frequency (treble) sliders are on the right.
Parametric Equalizers:
Another type of EQ is a parametric. A parametric EQ will allow for the adjustment of boost and cut of different bands like a graphic EQ but it allows the shifting of the frequency up or down the audio band. It may also allow for the adjustment of "Q" (the quality of the curve of the band passed by the filter). One drawback of the parametric EQ is that they usually have fewer bands than a graphic EQ but they can be extremely useful in fine tuning a system with only a few flaws in its frequency response.
Stereo vs Mono:
The terms stereo and mono are often used when referring to amplifier connections. A stereo amplifier has two independent channels, one left and one right. The left and right signals of the stereo signal are similar but not exactly the same. The two channels are used to give the audio a sense of depth. If one instrument or voice is only produced in the left channel, it will seem to originate from the left side of the listening area. If a particular sound is only slightly louder in one of the channels, that sound will seem to originate off center slightly toward the channel in which the sound is louder. If you have two speakers but supply mono signal to both of them, there will be no sense of separation or depth. If a mono signal fed to both channels of a stereo amplifier, with a speaker on each channel, the output will mono. If a stereo signal is fed to the same amp/speaker set up, the output will be stereo. If a speaker is bridged onto a stereo amplifier, the output of the speaker will be a mono output, even if the signal fed into the amplifier is a stereo signal. Even if 2 speakers are bridged onto the amplifier, the output will still be mono because the output from each speaker has the same content.
Basic Audio System Review:
The first link in the car audio chain is the stereo unit. The stereo unit most commonly contains a radio receiver and a mechanism for the playback of a recorded medium (tape or cd). The stereo unit can have speaker and/or preamp outputs. The speaker outputs will have enough current and voltage capacity to drive speakers. The preamp outputs do not have the current capacity to drive speakers. They are made to drive a high impedance input of an amplifier or equalizer. If your system has multiple amplifiers then you may need to put an electronic crossover between the stereo unit and the amplifiers. If the system has some part of the audio spectrum that is too loud or too low, then you may need to add an equalizer of some sort.
Wire Gauge
Recommended |
Maximum
Fuse Size |
| ------------------- |
------------- |
| 00 awg |
400 amps |
| 0 awg |
325 amps |
| 1 awg |
250 amps |
2 awg |
200 amps |
| 4 awg |
125 amps |
| 6 awg |
80 amps |
| 8 awg |
50 amps |
| 10 awg |
30 amps |
| 12 awg |
20 amps |
| 14 awg |
15 amps |
| 16 awg |
7.5 amps |
Terminology
- Channel - The path an audio signal travels through a circuit during playback. At least 2 channels are required for stereo sound
- Clipping - A distortion caused by cutting off the peaks of audio signals. Clipping usually occurs in the amplifier when it's input signal is too high or when the volume control is turned to high. Kind of like jumping on a trampoline inside with low ceilings.
- Crossover - A device that limits the range of frequencies sent to different speakers.
- Mono - monophonic sound. A method for reproducing sound where the signals from all directions or sources are blended into a single channel
- MOSFET - Metal Oxide Semiconductor Field Effect Transistors. Used in most modern, quality car audio amplifiers in the power supply (and sometimes in the output stage). MOSFET's run cooler than normal bipolar transistors, and have a faster switching speed.
- Out of Phase - when your speakers are mounted in reverse polarity, i.e., one speaker is wired +/+ and -/- from the amp and the other is wired +/- and -/+. Bass response will be very thin due to cancellation.
- RMS - an acronym for "root mean square." Used in audio to help rate the continuous power output of an amplifier or input capability of speakers. This is the preferred method for comparing anything in audio applications.
- Three-way - a type of speaker system composed of three ranges of speakers, specifically a woofer, midrange, and tweeter.
- Two-way - a type of speaker system composed of two ranges of speakers, usually a woofer and tweeter
- DIN - "Deutsches Institut für Normung" (DIN, the German Institute for Standardization), similar to ISO. The relevance for car DVD systems is that DIN means a standard sized dashboard slot, so 1 DIN means the device takes up one slot, and 2 DIN means the unit is ‘double-decker’ and uses the space of two slots.
- NTSC - National Television Standards Committee
Refers to the systems used by television broadcasts
The USA, Canada and Japan use the NTSC system.
- Remote controls - You may think a remote is for people too lazy to reach for their car stereo buttons. There are advantages to using a remote control. They're safer because they allow you to make changes without having to take your eyes off of the road. They also reduce the wear and tear on your head unit. Most head units have very small (sometimes cheaply made) switches for volume, track, station preset and such. If you repeatedly push these buttons with more force than necessary, they will fail. Replacing these small switches can be expensive. Using the remote allows these switches to last much longer and also allows the face plate around the buttons to remain as new. If the switches in the remote wear out, the remote can be replaced for less than the cost to repair the face of the head unit
- PAL - Phase alternating line
Refers to the systems used by television broadcasts
France, Greece and most "Eastern European" countries use SECAM. The rest of Europe uses PAL.
- In-dash - A device such as a Car DVD player installed in your dashboard, typically in the place of your old car radio.
- RF Modulator - A way to get an audio input source, (e.g. an MP3 player, iPod, CD player), into a radio signal so you can play it through your car stereo
- Power Handling (continuous or RMS) - A rating of the driver's ability in optimum conditions to handle a specified amount of audio power (electrical current power) on a constant basis, without damage. This is generally considered to be a conservative and reliable figure to use in judging what types of amplifier power will be most successful with a particular speaker design
- Peak Power Handling (MAX) - Peak power handling refers to the amount of power a speaker is estimated to handle during a brief high-intensity musical burst. Since this can vary with both frequency and amplitude, it is a much less accurate way to judge speaker durability and performance than RMS
- Monitor - A screen that receives a signal from (e.g. a Car DVD player or TV tuner) - if a product is described as a Monitor it typically means it does NOT include the actual input player, (e.g. Car DVD player unit).
- Motorized - where the TFT screen of a display, usually in a dashboard unit, automatically folds and slides inside its housing when not in use.
- Voice coil - The wire wound around the speaker former. The former is mechanically connected to the speaker cone and causes the cone to vibrate in response to the audio current in the voice coil.
- Double (Dual) Voice Coil (DVC) - a voice coil with two windings, generally subwoofers. Each voice coil can be connected to a stereo channel, or both voice coils can be wired in parallel or series to a single mono channel.
- Receiver - What transmits your video signal to a screen, (e.g. a Car DVD player)
- OEM - Original Equipment Manufacturer
- SVCD - Super Video Compact Disc
- VCD - Video Compact disc
- LCD - Liquid Crystal Display
- TFT - Thin Film Transistor
- GPS - Global Position Sensor
- WMA - Windows Media Player
- PLL - Phase Locked Loop
- IC - Integrated Chip aka microchip, chip, silicon chip, microcircuit
- AC - Alternating Current
- DC - Direct Current
- AWG - American Wire Gauge
- RMS - Root Mean Square
- ESP - Electronic Shock Protection
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